Over the years, Donald Trump and those working for him have had their differences over how much he owed them for their services.

“Let’s say that they do a job that’s not good, or a job that they didn’t finish, or a job that was way late. I’ll deduct from their contract, absolutely,” Trump said in an interview with USA Today, which found at least 60 lawsuits alleging Trump did not fully pay those who worked for him. “That’s what the country should be doing.”

Looks like this behavior may extend to his presidential campaign, as well: The self-proclaimed “King of Debt” reported more than$766,000 in “contested debt” for polling expenses to the firm of veteran pollster and political strategist Tony Fabrizio, on his latest FEC filing. The two-year old Florida-based Fabrizio, Lee & Associates LLC has been paid at least $623,000 so far by the campaign; earlier, the firm worked for Rand Paul’s 2016 campaign. The Trump campaign also reported $55,300 in debts to Fabrizio’s firm that are not disputed.

“It is the modus operandi for Donald Trump,” said Craig Holman, government affairs lobbyist for Public Citizen. “He’s always behaved that way throughout his business career. It comes as no surprise that he would be using a similar strategy with his presidential campaign.”

A representative from Fabrizio’s firm did not respond to multiple requests to comment. But it seems that conflicts with Fabrizio go back at least a few months. New York magazine reported recently that in July, Trump’s son-in-law, Jared Kushner, told Fabrizio that the campaign didn’t need to conduct focus groups. “I can tell from the applause what’s working,” Kushner reportedly said. (Kushner denies it.)

“This is an administrative issue that we’re resolving internally,” said Hope Hicks, the Trump campaign press secretary, in an email to OpenSecrets Blog. Hicks did not respond to questions about the disputed bill.

While debts are commonplace for campaigns, contested debts are fairly rare, Holman said. “When it comes to a contested debt, someone is literally trying not to pay and is claiming it is an invalid debt.”

The disagreement has to be resolved before the campaign committee can close. Frequently the two parties at odds in such situations come to some sort of settlement, but one party could surrender or file a lawsuit.

Although Trump said early in his campaign, “I don’t have pollsters, I don’t want to waste money on pollsters,” he has paid for some of them in the past months. Trump doled out about $673,000 since Aug. 30 to The Polling Company, run by his campaign manager, Kellyanne Conway. He has spent at least $2.4 million this year on expenses labeled as “polling.” More broadly, Trump has spent $6.4 million on “strategy and research” through his September filings.

Trump is not the first presidential candidate to report contested payments, though this seems to be among the largest disputes with a single vendor in recent history. Bill Clinton’s 1996 reelection campaign reported $218,000 in disputed debts on his July 2012 quarterly report. That included five different vendors for telephone, travel, consulting and event site rental payments. The issues were resolved and the committee finally closed in early 2014.

Al Gore’s 2000 presidential committee reported $388,000 in 12 separate disputed payments in his 2000 year-end report, the largest being around $300,000 to the Campaign Company for consulting/communications expenses. They were resolved the following year. While large, that’s still less than half of Trump’s contested debt to Fabrizio.

Clinton’s campaign has $111,000 in outstanding debt for a media buy, which is not reported to be disputed.

“Obviously in most cases, vendors and candidates don’t want to be going toe-to-toe over these sorts of debts,” Holman said. “It’s bad business for the vendor, and gives a bad career reputation for the candidate. For Donald Trump, there’s not so much civility.”